Lenses and lens combinations have been used in a variety of applications and devices for hundreds or even thousands of years. Numerous methods and systems for preparing lenses are known. Some examples include grinding, polishing, etching, and/or solidification of a liquid, such as a molten glass or liquid plastic. Grinding and polishing operations use precise machine or manual control to ensure that a precise desired curvature is obtained.
Grinding and polishing operations are, in general, not suitable for producing very small lenses or lens arrays. Etching methods, and particularly etching methods for lens arrays, can be heavily dependent upon acid resists being applied to a substrate in a desired accurate pattern. Etching methods can also be dependent upon differences or gradients in acid resistance of a substrate or upon carefully controlled compositions having particular etching rates.
The fabrication of small lenses and lens arrays may involve molding or surface tension during the solidification of a material from the liquid state (e.g., the cooling of molten glass) to form a desired lens curvature. Precise control in obtaining the desired lens curvature can be very difficult. When using surface tension to form the desired lens curvature, the lens surface curvature obtainable is generally restricted to the curvature naturally occurring in droplets of the liquid material. When forming small lenses and lens arrays, positioning and retaining a liquid at a precise desired location in a precise desired quantity can be difficult.